Ethylene polymers are conventionally used in a lot of fields, for example, used in extrusion molded articles such as films, sheets and the like. Extrusion molded articles are required be excellent in molding processability controlled by extrusion torque, melt tension and the like, mechanical properties such as rigidity, impact strength and the like, and further, appearances (optical properties) such as the surface smoothness, gloss, transparency and the like of a film or sheet.
For example, Japanese Patent Application No. 4-213309A describes an ethylene copolymers comprising a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 20 carbon atoms, wherein the density is from 0.86 to 0.95 g/cm3, MFR is from 0.001 to 50 g/10 minutes, the melt tension and MFR satisfy a specific relation, and the temperature at the position of the maximum peak of a heat absorption curve measured by DSC, and the density satisfy a specific relation, as an example of ethylene copolymers excellent in melt tension and having narrow composition distribution.
The above-mentioned ethylene copolymers described in JP.4-213309A has high melt tension, however, may not necessarily satisfy the requirements regarding the appearance of an extrusion molded article obtained from the copolymers, and there has been desired further improvement in the extrusion molding processability of an ethylene copolymer and in the balance between the appearance and impact strength of an extrusion molded article.